Galvanised gutter with timber cladding

[bluebellcottage]

We have galvanised steel guttering specified on our plans with western red cedar cladding. I have been advised that this isn’t a good idea as the tannic acid in the timber will damage the galvanised coating on the gutter. The same is apparently true of larch, oak, chestnut, douglas fir and cedar. 
 

I have contacted a few different guttering manufacturers and have been given similar but slightly differing advice. It seems the biggest issue will be that there will potentially be runoff from our dormer cheeks which will end up in the gutter.

 

i have seen lots of pictures online that appear to show timber cladding with ganvanised gutters, some of which state the cladding used as being western red cedar and wondered if anyone has real world experience of this?

 

another option to get a very similar look would be powder coated steel guttering which I have been told would be fine by one manufacturer and not by another.

 

any help would be very much appreciated.

 

[saveasteading]

You can paint the inside of the gutter with bitumen paint. 

We used to have such paint supplied as standard along with internal gutters. It had the physical advantages of stopping any repetitive drips from  wearing the galv off, and extra sealing at joints.

 

Now I think of it, there was aluminium dust mixed in which rose to the surface, which returned the sheen for reflecting the sun. I've no idea if that is a standard product. 

Use bitumen paint anyway and it will do what you need.

 

I would not recommend an internally  colour coated metal. It will laminate in time and the galvanising coat is minimal.

[Russell griffiths]

Can you change to aluminium gutter, is that any different. 

[Nick Laslett]

We used Ash thermowood cladding from QTD with Lindab coated Steel guttering. Been up 2 years, no issues yet.  

 

https://www.qtdgroup.com/thermowood-ash-cladding

 

https://upbuildingproducts.co.uk/products/steel-guttering/

 

Thermowood is more expensive, but it has a lot of long term benefits. 
 

*Edit: Advice from American Galvanisers Association 

 

Acidic woods or resinous/sappy woods such as cedar, pine, fur, and larch are aggressive to hot-dip galvanized steel and known to stain the HDG surface. Instead, dry, non-resinous wood species like poplar, ash, and spruce are recommended woods in contact with galvanized surfaces. Additional reference information regarding the corrosive effects of additional wood types are provided in Table 1.

 

https://galvanizeit.org/knowledgebase/article/corrosive-chemicals-and-galvanizing

 

 

Edited March 25 by Nick Laslett

[saveasteading]

58 minutes ago, Russell griffiths said:

aluminium gutter

One of the great disciplines on BH is saying nothing when you have nothing to say.

 

But I'm experienced in this, so it is duty to say...I don’t know.

 

Lindab is seriously good. So if they have a ready made product that suits,  then use it.

 

But I'm assuming the question is about an internal gutter, fabricated then galvanised. 

In such a situation I haven't heard of aluminium being used. Maybe it can. But the reasons against it may be strength and durability.

[Gone West]

We used Lindab guttering with Anthracite Grey polyester coating and had Western Red Cedar cladding and fascias. We didn't have any problems.

 

[Benpointer]

Damn and blast!  I think we might be in danger of making a big mistake with our cedar clad walls above zinc roof.  I've raised it with our archtect (though can't help feeling it should be the other way around 🤔)

 

[JohnMo]

We have a larch garage, they insisted galvanised nails were fine - black streaks everywhere 3 years later. Company disappeared.

 

If it isn't good stainless, do good plastic. You won't look at it month after installed.

 

Powder coat is pretty rubbish, stainless screws will make contact with carbon steel and cause corrosion - black streaks. Aluminium may not last long especially if coupled with stainless fixings you may not get black streaks but the aluminium will be eaten by stainless.

[JohnMo]

1 minute ago, Benpointer said:

zinc roof.

Zinc roof are or should be zinc, not galvanized steel. So shouldn't be an issue.

 

[Benpointer]

Just now, JohnMo said:

Zinc roof are or should be zinc, not galvanized steel. So shouldn't be an issue.

 

I wish it were so.  But according to VMZinc's website cedar and zinc are not compatible:  

 

"Acidic products and products that can generate a galvanic reaction must not be used with zinc.  Run-off from non compatible products onto zinc also must be avoided. In general, products with a ph lower than 5 and higher than 7 are not compatible with zinc.”
 

https://www.vmzinc.com/en-gb/technical-support/general-technical-recommendations/compatibility

 

 

[Nick Laslett]

According to this research paper, thermally modified Ash is more acidic and corrosive than regular Ash. Thermowood Ash had a pH value of 3.75.
 

Quote

The mean corrosion rate of ash nearly tripled from 12 to 37 μm year−1 when comparing the untreated and thermally modified wood

 

https://www.semanticscholar.org/reader/50b811003eb14f0d700560e08f45fe22cb8370c1

Edited March 25 by Nick Laslett

[Russell griffiths]

3 hours ago, saveasteading said:

One of the great disciplines on BH is saying nothing when you have nothing to say.

 

But I'm experienced in this, so it is duty to say...I don’t know.

 

Lindab is seriously good. So if they have a ready made product that suits,  then use it.

 

But I'm assuming the question is about an internal gutter, fabricated then galvanised. 

In such a situation I haven't heard of aluminium being used. Maybe it can. But the reasons against it may be strength and durability.

We have cedar cladding, and aluminium gutters, that’s why I mentioned it  

all came from a company called guttercrest, I find the Linda’s stuff a bit agricultural looking. 

[saveasteading]

18 minutes ago, Russell griffiths said:

Lindab’s stuff a bit agricultural looking

Agreed its chunky and modern. Not agricultural imo.

[saveasteading]

24 minutes ago, Russell griffiths said:

cedar cladding, and aluminium gutters

What is the interface? How does the timber contact the gutter? 

I had read the question as being the cedar can release acids somehow into the gutter.

5 hours ago, bluebellcottage said:

runoff from our dormer cheeks

 

[bluebellcottage]

Hello,

 

thank you for the input. I should have been more specific about the type of gutters. I am using standard gutters fixed to facia brackets. These will be on the pitched roof dormers as well as the main gutters at the eaves.
 

The facia boards are already fixed and are western red cedar. Each dormer cheek (5 dormers, so 10 in total) has a surface area of approximately 0.8m2, I am yet to clad these along with the front and rear portions of the house so could possibly use an alternative here.

 

my worries are.

 

1. Damage to the coating on the brackets where they touch the facia boards.

 

2. Damage to the gutters and downpipes from runoff from the dormer cheeks.

 

it was suggested by one manufacturer that using a rubber gasket between the facia and bracket could help with point 1.

 

down pipes will be fixed to brick using standard downpipes brackets. And spike brackets into the masonry behind the cladding where over cladding (this is due to the cladding being set 30mm back from the face of the brickwork and the facia boards.

 

 

 

 

[Russell griffiths]

5 hours ago, Benpointer said:

Damn and blast!  I think we might be in danger of making a big mistake with our cedar clad walls above zinc roof.  I've raised it with our archtect (though can't help feeling it should be the other way around 🤔)

 

Are you planning on letting it go grey, if you want to keep it a nice orange colour, if you want to keep it a nice orangey colour I think you might be better off with an artificial type cladding, something like TRESPA. 

[bluebellcottage]

@Benpointer from my research I believe you are correct and the tannic acid in the timber would/could damage the zinc via water runoff. What I don’t know is if this would happen over a period of a few months, years or over many years in which case it may not matter.

[bluebellcottage]

@saveasteading Lindab is my favoured brand due to the look, I prefer some of the little details over other brands.

 

i have also looked at Galeco and Zambelli.

 

originally i was looking at galvanised but one of the other manufacturers suggested using powdercoated in a suitable colour would be an option if I really wanted steel gutters.

[Benpointer]

7 minutes ago, Russell griffiths said:

Are you planning on letting it go grey, if you want to keep it a nice orange colour, if you want to keep it a nice orangey colour I think you might be better off with an artificial type cladding, something like TRESPA. 

We were planning on letting it silver naturally - we like that effect, had it on our previous house.  

 

We're now looking at Brimstone Poplar from Vastern. https://www.vastern.co.uk/timber-cladding/brimstone-poplar/ 

 

Poplar is noted on VMZinc's website as being compatible. https://www.vmzinc.com/en-gb/technical-support/general-technical-recommendations/compatibility

[Russell griffiths]

 

this is their poplar on my ceiling, substantial saving over cedar. @Benpointer

[saveasteading]

I don't use cedar, because I like the timber coloured. Others like the greying.

So I prefer softwood and sikkens.

 

But I think the original concern is overstated. How much acid? Rain would wash it away. 

Anyway, You can bitumen inside and relax.